JP 11-173188A published by the Japanese Patent Office in 1999 discloses a method of correcting the fuel supply amount during a startup period of an engine in response to the engine rotation speed. The startup period is defined as the period from initial combustion to complete combustion of the engine. Initial combustion is the first combustion after starting cranking of the engine with the starter motor. Complete combustion is a combustion state under which the engine rotates under its own power.
When the engine is started at a low temperature, the rotation speed is low due to the fact that friction creates high levels of resistance to rotation in the engine. The prior art technique achieves a preferred output torque by performing a correction to increase fuel supply when the rotation speed is low during the startup period.